package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.yaml.snakeyaml.events.Event;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;


    /**
     * @description: 根据id查询商铺信息
     * @params: [id]
     * @return:
     * @author: ajie
     * @date: 2024/2/14 15:47
     */
    @Override
    public Result queryById(Long id) {

        //缓存穿透
        //Shop shop = queryWithPassThrough(id);
//        Shop shop = cacheClient
//                .queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
        Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);
//        Shop shop = cacheClient
//                .queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        if (shop == null) {
            return Result.fail("店铺不存在！");
        }

        //返回
        return Result.ok(shop);

    }

    //创建线程池
    private static final ExecutorService CACHE_REBUILT_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * @description: 逻辑过期解决缓存击穿  根据id查询商铺信息
     * @params: [id]
     * @return:
     * @author: ajie
     * @date: 2024/2/14 21:27
     */
    public Shop queryWithLogicalExpire(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //判断是否命中
        if (StrUtil.isBlank(shopJson)) {
            //不存在，直接返回
            return null;
        }
        //命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //未过期，直接返回店铺信息
            return shop;
        }
        //已过期，需要缓存重建
        //缓存重建
        //获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //判断是否获取锁成功
        if (isLock) {
            //成功，开启独立线程，实现缓存重建
            CACHE_REBUILT_EXECUTOR.submit(() -> {
                try {
                    //重建缓存   30分钟过期
                    this.saveShop2Redis(id, 60 * 30L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }

        //返回过期的店铺信息
        return shop;
    }

    /**
     * @description: 互斥锁解决缓存击穿 根据id查询商铺信息
     * @params: [id]
     * @return:
     * @author: ajie
     * @date: 2024/2/14 21:00
     */
    public Shop queryWithMutex(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断命中的是否是空值
        if (shopJson != null) {
            //返回一个错误信息
            return null;
        }

        //实现缓存重建
        //获取互斥锁
        String lockKey = "lock:shop:" + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //判断是否获取成功
            if (!isLock) {
                //失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }

            //成功，根据id查询数据库
            shop = getById(id);
            //不存在，返回错误
            if (shop == null) {
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }
            //存在，写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //释放互斥锁
            unlock(lockKey);
        }

        //返回
        return shop;
    }

    /**
     * @description: 解决缓存穿透获取店铺信息
     * @params: [id]
     * @return:
     * @author: ajie
     * @date: 2024/2/14 19:36
     */
    public Shop queryWithPassThrough(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断命中的是否是空值
        if (shopJson != null) {
            //返回一个错误信息
            return null;
        }

        //不存在，根据id查询数据库
        Shop shop = getById(id);
        //不存在，返回错误
        if (shop == null) {
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            //返回错误信息
            return null;
        }
        //存在，写入redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //返回
        return shop;
    }

    /**
     * @description: 获取锁
     * @params: [key]
     * @return:
     * @author: ajie
     * @date: 2024/2/14 19:30
     */
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        //返回使用工具类，避免自动拆箱可能出翔空指针异常
        return BooleanUtil.isTrue(flag);
    }

    /**
     * @description: 释放锁
     * @params: [key]
     * @return:
     * @author: ajie
     * @date: 2024/2/14 19:30
     */
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }

    /**
     * @description: 店铺信息预热
     * @params: [id, expireSeconds]
     * @return:
     * @author: ajie
     * @date: 2024/2/14 21:24
     */
    public void saveShop2Redis(Long id, Long expireSeconds) {
        //查询店铺信息
        Shop shop = getById(id);
        //测试逻辑过期
//        try {
//            Thread.sleep(200);
//        } catch (InterruptedException e) {
//            throw new RuntimeException(e);
//        }

        //封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }

    /**
     * @description: 根据id更改店铺信息
     * @params: [shop]
     * @return:
     * @author: ajie
     * @date: 2024/2/14 19:29
     */
    @Override
    @Transactional
    public Result update(Shop shop) {

        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        //更新数据库
        updateById(shop);
        //删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //判断是否需要根据坐标查询
        if (x == null || y == null) {
            //不需要坐标查询，按照数据库查询
            Page<Shop> page = query().eq("type_id", typeId).page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            //返回数据
            return Result.ok(page.getRecords());
        }

        //计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        //查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        //geosearch key bylonlat x y byradius 10 withdistance
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        if (results == null){
            return Result.ok(Collections.emptyList());
        }
        //截取from ~ end 的部分
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from){
            //没有下一页，结束
            return Result.ok(Collections.emptyList());
        }
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result->{
            //获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });

        //根据id查询shop
        String idsStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("order by field(id," + idsStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }

        //返回
        return Result.ok(shops);

    }
}
